89 lines
1.9 KiB
Arduino
89 lines
1.9 KiB
Arduino
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// Basic demo for configuring the MCP4728 4-Channel 12-bit I2C DAC
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#include <Adafruit_MCP4728.h>
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#include <Wire.h>
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Adafruit_MCP4728 mcp;
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// idea behind this - sequence a cloud of gate events
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float hexany[] = { 0.12928301694496647, 0.32192809488736235, 0.3923174227787603, 0.5849625007211562, 0.8073549220576041, 0.9068905956085185 };
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float tuning[18];
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int chord[10] = { 0, 2, 4, 6, 8, 7, 11, 15, 14, 10 };
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int bpm = 60;
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float beat_s = 60.0 / (float)bpm;
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int beat_m = round(1000.0 * beat_s);
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float mod_b = 3.141592653589793 / 4.0;
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float voltrange = 4.85; // measured this, probably not accurate
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float octave = 4096.0 / voltrange; // number of DAC steps in an octave
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int gate = 0;
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int gatel = 1000;
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int tick = 16;
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long init_t;
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float p_gate = 0.0;
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void setup(void) {
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Serial.begin(115200);
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while (!Serial)
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delay(10); // will pause Zero, Leonardo, etc until serial console opens
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if (!mcp.begin(0x64)) {
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Serial.println("Failed to find MCP4728 chip");
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while (1) {
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delay(10);
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}
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Serial.println("MCP4728 initialised");
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}
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float n0 = 0;
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for( int o = 0; o < 3; o++ ) {
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for( int i = 0; i < 18; i++ ) {
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tuning[o * 6 + i] = round(n0 + octave * (o + hexany[i]));
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}
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}
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init_t = millis();
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mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
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}
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void loop() {
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int note;
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int k = 0;
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if( gate > 0 ) {
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gate--;
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if( gate == 0 ) {
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mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
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}
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} else {
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long now = millis();
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long mod_t = now - init_t;
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tick--;
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if( tick == 0 ) {
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tick = 32;
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p_gate = sin(mod_b * (float)mod_t / (float)beat_m);
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}
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if( (float)random(10000) / 20.0 < abs(p_gate)) {
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if( p_gate > 0 ) {
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note = random(5);
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} else {
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note = 5 + random(5);
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}
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mcp.setChannelValue(MCP4728_CHANNEL_B, 4095);
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mcp.setChannelValue(MCP4728_CHANNEL_A, tuning[note]);
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gate = gatel;
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}
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}
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}
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